Fluorescent spectrophotometric systems used for medical diagnostic analysis conventionally include a light source for exciting a fluorescent marker in a sample of biological fluid, such as a blood plasma sample. The light source excites the marker which, in turn, emits a fluorescent signal. The fluorescent signal is received by a light detector which measures the intensity of the emitted signal as a measure of the concentration of the biological parameter of interest. Such parameters can include, for example, plasma volume, glomerular filtration rate (GFR), and hematocrit. The spectrophotometric systems also include a means for storing spectrophotometric data, such as a digital memory storage device, a means for processing the spectrophotometric data, such as a digital computation processor, and an output for the processed data, such as a digital display. Typical fluorescent spectrophotometric systems used for the analysis of biomarkers, as well as methods for measuring biometric indicators, are disclosed in U.S. patent application Ser. Nos. 12/425,827 and 12/946,471, and PCT Patent Application Nos. PCT/US09/40994 and PCT/US10/32997.
In practice, a bolus injection containing one or more fluorescent markers, such as a dynamic marker and a static marker, is administered to the animal, and the change in concentration of the marker(s) is monitored over time to create an output data set. The data set can then be used to calculate the biological parameter of interest using mathematical models.
The accurate detection and measurement of the fluorescent marker is critical to the proper functioning of spectrophotometric analytical systems. Typically, a blood sample is taken from the patient and combined with a buffering solution and surfactant to form a medium for analysis. A light source is used to activate the fluorescent marker in the medium, and to generate fluorescent signals which are detected by a light detector. It has been found that in practice certain surfactants used in the medium can actually cause the suppression of the fluorescent signal, which can lead to errors in detection and false results supplied to the clinician.
Accordingly, it is a primary objective of the present invention to provide a composition and method for enhanced fluorescent signal detection from fluorescent markers used for the diagnosis of biological function and organ status in patients.
The present invention is intended to solve the problems discussed above, and to provide advantages not provided by prior techniques. A full discussion of the features and advantages of the present invention is deferred to the following detailed description, which also proceeds with reference to the accompanying drawings.